Laser process to produce drug delivery channel in metal stents

Abstract

A method for forming a stent and for also forming channels in the outer surface of selected regions of the stent structure. The method includes impinging a laser beam generated by a diode pumped Q-switched pulsed Nd / YAG laser operating at the third harmonic on an outer surface of a stent and controllably machining channels in the outer surface of the stent. The depth of the channels may be controlled by adjusting the power and pulse rate of the laser, and also by adjusting the rate at which the stent moves relative to the laser beam.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates generally to implantable medical devices and to a method for manufacturing implantable medical devices capable of retaining therapeutic materials and dispensing the therapeutic materials to a desired location of a patient's body. More particularly, the present invention relates to an implantable medical device, such as a stent or other intravascular or intraductal medical device, and to a method for forming channels, depots, holes or other indented structures in the structure of the stent or intravascular or intraductal medical device capable of holding a therapeutic material that is dispensed from the stent or other medical device when the stent or other medical device is implanted within a lumen or duct of the patient. [0003] 2. General Background and State of the Art [0004] In a typical percutaneous transluminal coronary angioplasty (PTCA) for compressing lesion plaque against the ar...

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Benefits of technology

[0019] In yet another aspect of the present invention, the Nd / YAG and diode pumped Q-switched lasers are mounted on the same cutting apparatus such that the laser beams utilize the same positioning system. In this manner, registration inaccuracies associated with removal of the stent from the stent pattern cutting equipment and remounting the stent in the channel machining equipment are avoided.

[0022] In a still further aspect of the present invention, the method includes delaying exposing the stent structure to the channel cutting laser beam for a selected period of time after beginning to move the stent relative to the laser beam. This method is advantageous in that it accommodates the lag in motion of the precision machinery relative to the initiation of the laser beam that may result in the beginning portion of the channel having greater depth than a portion of the channel that was exposed to the laser beam after the relative motion between the stent and the laser beam has begun.

Problems solved by technology

Although the stents are effective in opening the stenotic lumen, the foreign material and structure of the stents themselves may exacerbate the occurrence of restenosis or thrombosis.

Although PTCA and related procedures aid in alleviating intraluminal constrictions, such constrictions or blockages reoccur in many cases.

As such, one drawback associated with the systemic application of drugs is that areas of the body not needing treatment are also affected.

A problem with delivering therapeutic substances from a stent is that, because of the limited size of the stent, the total amount of therapeutic substance that can be carried by the stent is limited.

Furthermore, when the stent is implanted into a blood vessel, much of the released therapeutic substance enters the blood stream before it can benefit the damaged tissue.

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